2150 Carb Question - name the part!

[Scoop]

Carb gurus: What are the 2 parts circled? What do they do and does the left one look damaged??

 

[half cab]

Air metering rods.they rise up and down metering the air fuel flow. Should move together.
,
I can't tell about the damage from my ph.

 

[Scoop]

Thanks. I'm having idle issues - can't get the idle speed low enough. It wants to idle at 1100-1200 RPM with the idle speed screw backed all the way off. Could this be the issue if one is not seated all the way?

 

[half cab]

Pull the top on off and see why the one is not rising up with the other? I would think it definitely would effect idle. Might just be stuck or out of the lil clip thingy? Be careful with the brass arms they are fragile and will snap! Ask me how I know and as far as I know none of the parts stores carry them.

 

[half cab]

Gary, PM. member jckkys he's the guru on carbs. Should be able to tell you exactly what you need to do and more then likely have something if you need it.

 

[broncnaz]

Im not sure if the rods being bent will affect idle quality as the idle is a different circuit but you'll find out once you get it seated again. You most likely have a vacuum leak thats keeping the idle speed up. Check all vacuum lines and around the base of the carb for any leaks. You may also want to check your throttle linkage make sure its not holding the throttle open a little. disconnect it and restart the engine to see if that was the issue..

 

[jckkys]

The tapered rods vary the amount of air entering the high speed air bleeds. As the throttle opens a cam on the throttle shaft that lifts the rod and hanger raising the tapered metering rods to reduce the air flow and make the mixture richer. One of yours is stuck in the raised position. They should hang in loose in the hole. You may have dirt or a misaligned booster cluster gasket that won't allow it to move freely. I doubt there's any damage. Since this only effects the main system, it has no influence on the idle system. The cruising A/F mixture to 4 cylinders is likely too rich killing your MPGs. The 2100-2150s have a hollow base that needs a good seal at the mounting gasket to avoid vacuum leaks, but it does appear there's a vacuum leak as broncnaz points out. It could be in many places. To fix the air bleed metering rod it's best to remove the top cover and booster cluster to see what's up.

 

[Toddpole]

Gary,
That carb is old and most likely not a wise choice for your stock street ride. Might I suggest an upgrade to one of these beauties? Imagine how quickly you can get to the grocery store and back. ; )

 

[Scoop]

Gary,
That carb is old and most likely not a wise choice for your stock street ride. Might I suggest an upgrade to one of these beauties? Imagine how quickly you can get to the grocery store and back. ; )

What is that? A huge single barrel??

 

[Toddpole]

What is that? A huge single barrel??

The square one in the first picture is a Predator. I'm sure you've heard of those. The second is a huge single venture based on a standard double pumper size body. Looks like a grapefruit would pass thru that thing.
http://www.prosystemsracing.com/041411scoop.html

 

[jckkys]

A real upgrade from a 2150 isn't a racing carb. A case could be made for a 4100 if you're willing to get a 4bbl intake. Even then, you would see no improvement under most driving conditions. Over size racing carburetors hurt drive abillity and MPGs with no upside. The idea that newer equals better is foolish. The needs of a 4X4 truck or daily driver were not a consideration with racing carbs. Racing carburetors are made for racing engines being operated at full throttle. On a stock 302 there's no improvement in torque or HP.

 

[Scoop]

A real upgrade from a 2150 isn't a racing carb. A case could be made for a 4100 if you're willing to get a 4bbl intake. Even then, you would see no improvement under most driving conditions. Over size racing carburetors hurt drive abillity and MPGs with no upside. The idea that newer equals better is foolish. The needs of a 4X4 truck or daily driver were not a consideration with racing carbs. Racing carburetors are made for racing engines being operated at full throttle. On a stock 302 there's no improvement in torque or HP.

I assumed Toddpole's post was was in jest!

The tapered rods vary the amount of air entering the high speed air bleeds. As the throttle opens a cam on the throttle shaft that lifts the rod and hanger raising the tapered metering rods to reduce the air flow and make the mixture richer. One of yours is stuck in the raised position. They should hang in loose in the hole. You may have dirt or a misaligned booster cluster gasket that won't allow it to move freely. I doubt there's any damage. Since this only effects the main system, it has no influence on the idle system. The cruising A/F mixture to 4 cylinders is likely too rich killing your MPGs. The 2100-2150s have a hollow base that needs a good seal at the mounting gasket to avoid vacuum leaks, but it does appear there's a vacuum leak as broncnaz points out. It could be in many places. To fix the air bleed metering rod it's best to remove the top cover and booster cluster to see what's up.

jckkys, thanks for the info. I'll take it apart further and see what's up. As for a vacuum leak, this was my first guess and I have looked several times for one. The carb is mounted on a phenolic spacer but appears to be sealed good at the base. I have used map gas to check for leaks at all the vacuum connections and around the carb. It does get a slight blip in rpm at the throttle shaft on the driver's side. Other than that no leaks I could detect.

 

[jckkys]

It looks like a rebuild of the 2150 is the best way to address both your problems. After that, diagnoses will be easier.